In many parts of the world, it is necessary to provide cement compositions which will flow and set in low temperature or freezing environments. For example, in parts of the world it is desired to cement casing through permafrost regions where the temperature is below 32.degree. F. One cement system developed for these purposes is disclosed by Holmgren et al. in U.S. Pat. No. 3,179,528. That composition consists of a mixture of portland cement, gypsum, an aqueous solution of a lower aliphatic alcohol as a freeze depressant and glue size to control the pumpability time at temperatures below freezing. One drawback to this cement system is the fact that increased temperatures reduce the pumping time so that the cement must at all times be kept at low temperatures, i.e. approximately at freezing point of water and below. Because of this characteristic short pumping time at elevated temperatures, special cementing procedures and equipment must be employed in cementing, for example, borehole casing in wells which are drilled through permafrost and then into areas reaching elevated temperatures, for example, 100.degree. F. or greater. In these particular situations, a by-pass tool must be employed to prevent the freeze protected cement from entering into the higher temperature zones wherein it may set up and prevent further cementing operations on the well.
Other art which is relevant to the present invention are Federal Republic of Germany Pat. Nos. 706,404, 936,673, and 936,318; and U.S. Pat. Nos. 3,071,481 (Beach et al.), 3,582,376 (Ames), 3,782,992 (Uchikawa et al.), and 3,891,454 (Cunningham et al.). In a commonly assigned copending application of Duane L. Stude and Earl F. Morris, Ser. No. 438,492 filed Jan. 31, 1974, it is disclosed that compositions similar to those of Cunningham et al. can be pumped through warm zones above 80.degree. F. and thence into cooler zones, e.g. below freezing, where the compositions will set. A low temperature cement composition containing urea is disclosed in another commonly assigned copending application by Duane L. Stude, Ser. No. 662,666, filed Mar. 1, 1976.
The present invention comprises a cement composition which, upon addition of water, forms a slurry which sets up at low temperatures, i.e. below 80.degree. F. to below freezing, within a suitable period of time to provide a monolithic mass having adequate compressive strength. The invention also comprises a method of cementing under such temperature conditions.